Phase Ib study of sabatolimab (MBG453), a novel immunotherapy targeting TIM-3 antibody, in combination with decitabine or azacitidine in high- or very high-risk myelodysplastic syndromes.

The safety and efficacy of sabatolimab, a novel immunotherapy targeting T-cell immunoglobulin domain and mucin domain-3 (TIM-3), was assessed in combination with hypomethylating agents (HMAs) in patients with HMA-naive revised International Prognostic System Score (IPSS-R) high- or very high-risk myelodysplastic syndromes (HR/vHR-MDS) or chronic myelomonocytic leukemia (CMML). Sabatolimab + HMA had a safety profile similar to that reported for HMA alone and demonstrated durable clinical responses in patients with HR/vHR-MDS. These results support the ongoing evaluation of sabatolimab-based combination therapy in MDS, CMML, and acute myeloid leukemia.

Adjunctive Volasertib in Patients With Acute Myeloid Leukemia not Eligible for Standard Induction Therapy: A Randomized, Phase 3 Trial.

In this phase 3 trial, older patients with acute myeloid leukemia ineligible for intensive chemotherapy were randomized 2:1 to receive the polo-like kinase inhibitor, volasertib (V; 350 mg intravenous on days 1 and 15 in 4-wk cycles), combined with low-dose cytarabine (LDAC; 20 mg subcutaneous, twice daily, days 1-10; n = 444), or LDAC plus placebo (P; n = 222). Primary endpoint was objective response rate (ORR); key secondary endpoint was overall survival (OS). Primary ORR analysis at recruitment completion included patients randomized ≥5 months beforehand; ORR was 25.2% for V+LDAC and 16.8% for P+LDAC (n = 371; odds ratio 1.66 [95% confidence interval (CI), 0.95-2.89]; P = 0.071). At final analysis (≥574 OS events), median OS was 5.6 months for V+LDAC and 6.5 months for P+LDAC (n = 666; hazard ratio 0.97 [95% CI, 0.8-1.2]; P = 0.757). The most common adverse events (AEs) were infections/infestations (grouped term; V+LDAC, 81.3%; P+LDAC, 63.5%) and febrile neutropenia (V+LDAC, 60.4%; P+LDAC, 29.3%). Fatal AEs occurred in 31.2% with V+LDAC versus 18.0% with P+LDAC, most commonly infections/infestations (V+LDAC, 17.1%; P+LDAC, 6.3%). Lack of OS benefit with V+LDAC versus P+LDAC may reflect increased early mortality with V+LDAC from myelosuppression and infections.

Dynamics of mutations in patients with essential thrombocythemia treated with imetelstat.

In a phase-2 study, the telomerase inhibitor imetelstat induced rapid hematologic responses in all patients with essential thrombocythemia who were refractory or intolerant to prior therapies. Significant molecular responses were achieved within 3-6 months in 81% of patients with phenotypic driver mutations in JAK2, CALR and MPL. Here, we investigated the dynamics of additional somatic mutations in response to imetelstat. At study entry, 50% of patients carried 1-5 additional mutations in the genes ASXL1, CBL, DNMT3A, EZH2, IDH1, SF3B1, TET2, TP53 and U2AF1. Three patients with baseline mutations also had late-emerging mutations in TP53, IDH1 and TET2. Most clones with additional mutations were responsive to imetelstat and decreased with the driver mutation, including the poor prognostic ASXL1, EZH2 and U2AF1 mutations while SF3B1 and TP53 mutations were associated with poorer molecular response. Overall, phenotypic driver mutation response was significantly deeper in patients without additional mutations (P = 0.04) and correlated with longer duration of response. In conclusion, this detailed molecular analysis of highly pretreated and partly resistant patients with essential thrombocythemia reveals a high individual patient complexity. Moreover, imetelstat demonstrates potential to inhibit efficiently co-incident mutations occurring in neoplastic clones in patients with essential thrombocythemia. (ClinicalTrials.gov number, NCT01243073. N Engl J Med 2015; 373:920-928, DOI: 10.1056/NEJMoa1503479.).

A phase I study of a dual PI3-kinase/mTOR inhibitor BEZ235 in adult patients with relapsed or refractory acute leukemia.

BACKGROUND: Combined inhibition of phosphatidylinositol 3-kinase (PI3K) and the mammalian target of rapamycin (mTOR) complexes may be an efficient treatment for acute leukemia. The primary objective of this phase I single center open label study was to determine the maximum tolerated dose (MTD) and recommended phase II dose (RP2D) of the dual pan-class I PI3K and mTOR inhibitor BEZ235 in patients with advanced leukemia. METHODS: Herein patients > 18 years of age who had relapsed or showed refractory leukemia were treated with BEZ235 (orally at 300-400 mg BID (cohort - 1/1)) to assess safety, tolerability, preliminary efficacy and pharmacokinetic (PK). Adverse events data and serious adverse events were analyzed and haematological and clinical biochemistry toxicities were assessed from laboratory test parameters. Response was assessed for the first time at the end of cycle 1 (day 29) and after every subsequent cycle. Pharmacokinetic and pharmacodynamic analyses of BEZ235 were also included (BEZ235 plasma levels, phosphorylation of AKT, S6 and 4EBP1). On statistics this trial is a multiple ascending dose study in which a following variant of the 3 + 3 rule ("Rolling Six"), a minimum of 6 and a maximum of 12 patients was recruited for the dose escalation and another 5 were planned for the expansion phase. RESULTS: Twenty-four patients with ALL (n = 11) or AML (n = 12) or CML-BP (n = 1) were enrolled. All patients had failed one (n = 5) or more lines of therapy (n = 5) and 14 patients were in refractory / refractory relapse. No formal MTD was defined, stomatitis and gastrointestinal toxicity at 400 mg BID dose was considered incompatible with prolonged treatment. The RP2D of BEZ235 was defined as 300 mg BID. Four of 24 patients showed clinical benefit. Twenty-two of 24 patients discontinued because of progression, (median time to progression 27 days (4d-112d). There was no association between PK parameters and efficacy or tolerability. CONCLUSIONS: Combined inhibition of PI3K and mTOR inhibits a clinically meaningful driver pathway in a small subset of patients with ALL, with no benefit in patients with AML. TRIAL REGISTRATION: ClinicalTrials.gov , identifier NCT01756118. retrospectively registered 19th December 2012, https://clinicaltrials.gov/ct2/show/NCT01756118 .

Blinatumomab compared with standard of care for the treatment of adult patients with relapsed/refractory Philadelphia chromosome-positive B-precursor acute lymphoblastic leukemia.

BACKGROUND: A single-arm, phase 2 trial demonstrated the efficacy and safety of blinatumomab, a bispecific T-cell-engaging antibody construct, in patients with relapsed/refractory (r/r) Philadelphia chromosome-positive (Ph+) acute lymphoblastic leukemia (ALL), a rare hematologic malignancy with limited treatment options. This study compared outcomes with blinatumomab with those of a historical control treated with the standard of care (SOC). METHODS: The blinatumomab trial enrolled adult patients with Ph+ ALL who were r/r to at least 1 second-generation tyrosine kinase inhibitor (n = 45). Propensity score analysis (PSA) was used to compare outcomes with blinatumomab with those of an external cohort of similar patients receiving SOC chemotherapy (n = 55). The PSA mitigated confounding variables between studies by adjusting for imbalances in the age at diagnosis and start of treatment, sex, duration from diagnosis to most recent treatment, prior allogeneic hematopoietic stem cell transplantation, prior salvage therapy, and number of salvage therapies. Bayesian data augmentation was applied to improve power to 80% with data from a phase 3 blinatumomab study in r/r Philadelphia chromosome-negative ALL. RESULTS: In the PSA, the rate of complete remission or complete remission with partial hematologic recovery was 36% for blinatumomab and 25% for SOC, and this resulted in an odds ratio of 1.54 (95% confidence interval [CI], 0.61-3.89) or 1.70 (95% credible interval [CrI], 0.94-2.94) with Bayesian data augmentation. Overall survival favored blinatumomab over SOC, with a hazard ratio of 0.81 (95% CI, 0.57-1.14) or 0.77 (95% CrI, 0.61-0.96) with Bayesian data augmentation. CONCLUSIONS: These results further support blinatumomab as a treatment option for patients with r/r Ph+ ALL.

Genomic CDKN2A/2B deletions in adult Ph+ ALL are adverse despite allogeneic stem cell transplantation.

We investigated the role of copy number alterations to refine risk stratification in adult Philadelphia chromosome positive (Ph)+ acute lymphoblastic leukemia (ALL) treated with tyrosine kinase inhibitors (TKIs) and allogeneic stem cell transplantation (aSCT). Ninety-seven Ph+ ALL patients (median age 41 years; range 18-64 years) within the prospective multicenter German Multicenter ALL Study Group studies 06/99 (n = 8) and 07/2003 (n = 89) were analyzed. All patients received TKI and aSCT in first complete remission (CR1). Copy number analysis was performed with single nucleotide polymorphism arrays and validated by multiplex ligation-dependent probe amplification. The frequencies of recurrently deleted genes were: IKZF1, 76%; CDKN2A/2B, 45%; PAX5, 43%; BTG1, 18%; EBF1, 13%; ETV6, 5%; RB, 14%. In univariate analyses, the presence of CDKN2A/2B deletions had a negative impact on all endpoints: overall survival (P = .023), disease-free survival (P = .012), and remission duration (P = .036). The negative predictive value of CDKN2A/2B deletions was retained in multivariable analysis along with other factors such as timing of TKI therapy, intensity of conditioning, achieving remission after induction phase 1 and BTG1 deletions. We therefore conclude that acquired genomic CDKN2A/2B deletions identify a subgroup of Ph+ ALL patients, who have an inferior prognosis despite aSCT in CR1. Their poor outcome was attributable primarily to a high relapse rate after aSCT.

CRISPR-mediated TCR replacement generates superior anticancer transgenic T cells.

Adoptive transfer of T cells genetically modified to express a cancer-specific T-cell receptor (TCR) has shown significant therapeutic potential for both hematological and solid tumors. However, a major issue of transducing T cells with a transgenic TCR is the preexisting expression of TCRs in the recipient cells. These endogenous TCRs compete with the transgenic TCR for surface expression and allow mixed dimer formation. Mixed dimers, formed by mispairing between the endogenous and transgenic TCRs, may harbor autoreactive specificities. To circumvent these problems, we designed a system where the endogenous TCR-ß is knocked out from the recipient cells using clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein-9 (Cas9) technology, simultaneously with transduction with a cancer-reactive receptor of choice. This TCR replacement strategy resulted in markedly increased surface expression of transgenic αß and γδ TCRs, which in turn translated to a stronger, and more polyfunctional, response of engineered T cells to their target cancer cell lines. Additionally, the TCR-plus-CRISPR-modified T cells were up to a thousandfold more sensitive to antigen than standard TCR-transduced T cells or conventional model proxy systems used for studying TCR activity. Finally, transduction with a pan-cancer-reactive γδ TCR used in conjunction with CRISPR/Cas9 knockout of the endogenous αß TCR resulted in more efficient redirection of CD4+ and CD8+ T cells against a panel of established blood cancers and primary, patient-derived B-cell acute lymphoblastic leukemia blasts compared with standard TCR transfer. Our results suggest that TCR transfer combined with genome editing could lead to new, improved generations of cancer immunotherapies.

Dasatinib and Azacitidine Followed by Haploidentical Stem Cell Transplant for Chronic Myeloid Leukemia with Evolving Myelodysplasia: A Case Report and Review of Treatment Options.

BACKGROUND CML presenting with a variant Philadelphia translocation, atypical BCR-ABL transcript, additional chromosomal aberrations, and evolving MDS is uncommon and therapeutically challenging. The prognostic significance of these genetic findings is uncertain, even as singular aberrations, with nearly no data on management and outcome when they coexist. MDS evolving during the course of CML may be either treatment-associated or an independently coexisting disease, and is generally considered to have an inferior prognosis. Tyrosine kinase inhibitors (TKI) directed against BCR-ABL are the mainstay of treatment for CML, whereas treatment modalities that may be utilized for MDS and CML include allogeneic stem cell transplant and - at least conceptually - hypomethylating agents. CASE REPORT Here, we describe the clinical course of such a patient, demonstrating that long-term combined treatment with dasatinib and azacitidine for coexisting CML and MDS is feasible and well tolerated, and may be capable of slowing disease progression. This combination therapy had no deleterious effect on subsequent potentially curative haploidentical bone marrow transplantation. CONCLUSIONS The different prognostic implications of this unusual case and new therapeutic options in CML are discussed, together with a review of the current literature on CML presenting with different types of genomic aberrations and the coincident development of MDS. Additionally, this case gives an example of long-term combined treatment of tyrosine kinase inhibitors and hypomethylating agents, which could be pioneering in CML treatment.

Continuously expanding CAR NK-92 cells display selective cytotoxicity against B-cell leukemia and lymphoma.

BACKGROUND AIMS: Natural killer (NK) cells can rapidly respond to transformed and stressed cells and represent an important effector cell type for adoptive immunotherapy. In addition to donor-derived primary NK cells, continuously expanding cytotoxic cell lines such as NK-92 are being developed for clinical applications. METHODS: To enhance their therapeutic utility for the treatment of B-cell malignancies, we engineered NK-92 cells by lentiviral gene transfer to express chimeric antigen receptors (CARs) that target CD19 and contain human CD3ζ (CAR 63.z), composite CD28-CD3ζ or CD137-CD3ζ signaling domains (CARs 63.28.z and 63.137.z). RESULTS: Exposure of CD19-positive targets to CAR NK-92 cells resulted in formation of conjugates between NK and cancer cells, NK-cell degranulation and selective cytotoxicity toward established B-cell leukemia and lymphoma cells. Likewise, the CAR NK cells displayed targeted cell killing of primary pre-B-ALL blasts that were resistant to parental NK-92. Although all three CAR NK-92 cell variants were functionally active, NK-92/63.137.z cells were less effective than NK-92/63.z and NK-92/63.28.z in cell killing and cytokine production, pointing to differential effects of the costimulatory CD28 and CD137 domains. In a Raji B-cell lymphoma model in NOD-SCID IL2R γnull mice, treatment with NK-92/63.z cells, but not parental NK-92 cells, inhibited disease progression, indicating that selective cytotoxicity was retained in vivo. CONCLUSIONS: Our data demonstrate that it is feasible to generate CAR-engineered NK-92 cells with potent and selective antitumor activity. These cells may become clinically useful as a continuously expandable off-the-shelf cell therapeutic agent.

Chimeric antigen receptor-engineered cytokine-induced killer cells overcome treatment resistance of pre-B-cell acute lymphoblastic leukemia and enhance survival.

Pre-emptive cancer immunotherapy by donor lymphocyte infusion (DLI) using cytokine-induced killer (CIK) cells may be beneficial to prevent relapse with a reduced risk of causing graft-versus-host-disease. CIK cells are a heterogeneous effector cell population including T cells (CD3(+) CD56(-) ), natural killer (NK) cells (CD3(-) CD56(+) ) and natural killer T (T-NK) cells (CD3(+) CD56(+) ) that exhibit non-major histocompatibility complex (MHC)-restricted cytotoxicity and are generated by ex vivo expansion of peripheral blood mononuclear cells in the presence of interferon (IFN)-γ, anti-CD3 antibody, interleukin-2 (IL-2) and interleukin-15 (IL-15). To facilitate selective target-cell recognition and enhance specific cytotoxicity against B-cell acute lymphoblastic leukemia (B-ALL), we transduced CIK cells with a lentiviral vector encoding a chimeric antigen receptor (CAR) that carries a composite CD28-CD3ζ domain for signaling and a CD19-specific scFv antibody fragment for cell binding (CAR 63.28.z). In vitro analysis revealed high and specific cell killing activity of CD19-targeted CIK/63.28.z cells against otherwise CIK-resistant cancer cell lines and primary B-ALL blasts, which was dependent on CD19 expression and CAR signaling. In a xenograft model in immunodeficient mice, treatment with CIK/63.28.z cells in contrast to therapy with unmodified CIK cells resulted in complete and durable molecular remissions of established primary pre-B-ALL. Our results demonstrate potent antileukemic activity of CAR-engineered CIK cells in vitro and in vivo, and suggest this strategy as a promising approach for adoptive immunotherapy of refractory pre-B-ALL.

Dasatinib and low-intensity chemotherapy in elderly patients with Philadelphia chromosome-positive ALL.

Prognosis of Philadelphia-positive (Ph(+)) acute lymphoblastic leukemia (ALL) in the elderly has improved during the imatinib era. We investigated dasatinib, another potent tyrosine kinase inhibitor, in combination with low-intensity chemotherapy. Patients older than age 55 years were included in the European Working Group on Adult ALL (EWALL) study number 01 for Ph(+) ALL (EWALL-PH-01 international study) and were treated with dasatinib 140 mg/day (100 mg/day over 70 years) with intrathecal chemotherapy, vincristine, and dexamethasone during induction. Patients in complete remission continued consolidation with dasatinib, sequentially with cytarabine, asparaginase, and methotrexate for 6 months. Maintenance therapy was dasatinib and vincristine/dexamethasone reinductions for 18 months followed by dasatinib until relapse or death. Seventy-one patients with a median age of 69 years were enrolled; 77% had a high comorbidity score. Complete remission rate was 96% and 65% of patients achieved a 3-log reduction in BCR-ABL1 transcript levels during consolidation. Only 7 patients underwent allogeneic hematopoietic stem cell transplantation. At 5 years, overall survival was 36% and up to 45% taking into account deaths unrelated to disease or treatment as competitors. Thirty-six patients relapsed, 24 were tested for mutation by Sanger sequencing, and 75% were T315I-positive. BCR-ABL1(T315I) was tested by allele-specific oligonucleotide reverse transcription-quantitative polymerase chain reaction in 43 patients and detection was associated with short-term relapses. Ten patients (23%) were positive before any therapy and 8 relapsed, all with this mutation. In conclusion, dasatinib combined with low-intensity chemotherapy was well-tolerated and gave long-term survival in 36% of elderly patients with Ph(+) ALL. Monitoring of BCR-ABL1(T315I) from diagnosis identified patients with at high risk of early relapse and may help to personalize therapy.

CD19-CAR engineered NK-92 cells are sufficient to overcome NK cell resistance in B-cell malignancies.

Many B-cell acute and chronic leukaemias tend to be resistant to killing by natural killer (NK) cells. The introduction of chimeric antigen receptors (CAR) into T cells or NK cells could potentially overcome this resistance. Here, we extend our previous observations on the resistance of malignant lymphoblasts to NK-92 cells, a continuously growing NK cell line, showing that anti-CD19-CAR (αCD19-CAR) engineered NK-92 cells can regain significant cytotoxicity against CD19 positive leukaemic cell lines and primary leukaemia cells that are resistant to cytolytic activity of parental NK-92 cells. The 'first generation' CAR was generated from a scFv (CD19) antibody fragment, coupled to a flexible hinge region, the CD3ζ chain and a Myc-tag and cloned into a retrovirus backbone. No difference in cytotoxic activity of NK-92 and transduced αCD19-CAR NK-92 cells towards CD19 negative targets was found. However, αCD19-CAR NK-92 cells specifically and efficiently lysed CD19 expressing B-precursor leukaemia cell lines as well as lymphoblasts from leukaemia patients. Since NK-92 cells can be easily expanded to clinical grade numbers under current Good Manufactoring Practice (cGMP) conditions and its safety has been documented in several phase I clinical studies, treatment with CAR modified NK-92 should be considered a treatment option for patients with lymphoid malignancies.

Blockade of thymic stromal lymphopoietin (TSLP) receptor inhibits TSLP-driven proliferation and signalling in lymphoblasts from a subset of B-precursor ALL patients.

PURPOSE: The cytokine thymic stromal lymphopoietin (TSLP) and its receptor TSLPR are involved in intercellular communication in the course of allergic inflammation and have recently been implicated in the development of various malignancies including B cell precursor acute lymphoblastic leukemia (BCP-ALL). We studied TSLPR expression, TSLP-induced signal transduction and its antibody-mediated inhibition in long-term cultures of primary cells derived from B-precursor ALL patients. METHODS: TSLPR expression was determined by flow cytometry and Western blot analysis, cell proliferation, signal transduction via the JAK/STAT pathway was analysed by Western blot detection of STAT tyrosine phosphorylation and by measuring TSLP-dependent activation of a STAT-specific reporter gene construct. For inhibition studies a recently introduced antagonistic antibody to the TSLPRα-subunit was used. RESULTS: TSLPR surface expression was observed in leukemic lymphoblasts from two out of ten patients with BCP-ALL. Upon TSLP stimulation, the cells with the highest TSLPR expression level showed enhanced proliferation and JAK/STAT-mediated gene regulation in a dose-dependent manner. By employment of an inhibitory antibody to the TSLPR, both TSLP-triggered cell proliferation and STAT transcription factor activation were specifically inhibited. CONCLUSIONS: These results suggest that blockade of the TSLPR might be a therapeutic option for a subset of BCP-ALL patients.

Telomerase Inhibitor Imetelstat in Patients with Essential Thrombocythemia.

BACKGROUND: Imetelstat, a 13-mer oligonucleotide that is covalently modified with lipid extensions, competitively inhibits telomerase enzymatic activity. It has been shown to inhibit megakaryocytic proliferation in vitro in cells obtained from patients with essential thrombocythemia. In this phase 2 study, we investigated whether imetelstat could elicit hematologic and molecular responses in patients with essential thrombocythemia who had not had a response to or who had had unacceptable side effects from prior therapies. METHODS: A total of 18 patients in two sequential cohorts received an initial dose of 7.5 or 9.4 mg of imetelstat per kilogram of body weight intravenously once a week until attainment of a platelet count of approximately 250,000 to 300,000 per cubic millimeter. The primary end point was the best hematologic response. RESULTS: Imetelstat induced hematologic responses in all 18 patients, and 16 patients (89%) had a complete hematologic response. At the time of the primary analysis, 10 patients were still receiving treatment, with a median follow-up of 17 months (range, 7 to 32 [ongoing]). Molecular responses were seen in 7 of 8 patients who were positive for the JAK2 V617F mutation (88%; 95% confidence interval, 47 to 100). CALR and MPL mutant allele burdens were also reduced by 15 to 66%. The most common adverse events during treatment were mild to moderate in severity; neutropenia of grade 3 or higher occurred in 4 of the 18 patients (22%) and anemia, headache, and syncope of grade 3 or higher each occurred in 2 patients (11%). All the patients had at least one abnormal liver-function value; all persistent elevations were grade 1 or 2 in severity. CONCLUSIONS: Rapid and durable hematologic and molecular responses were observed in patients with essential thrombocythemia who received imetelstat. (Funded by Geron; ClinicalTrials.gov number, NCT01243073.).